Steering mechanism in a boat propulsion system

ABSTRACT

A marine propulsion drive apparatus has an input drive shaft with a propeller shaft extending through the stern of the boat and a drive body extending substantially straight out the stern of the boat and having a propeller at the end thereof. Steering is accomplished by operating the drive body itself. The drive body and the stern of the boat have a common oblique upward rearward slope. The contact surface of the drive body is mounted rotatably about an axis which is perpendicular to the contact surface such that when the boat is turned in one direction or the other, the entire drive body with the propeller mechanism is rotated about that contact surface, such that the propeller mechanism at the outer end of the drive body both rotates in the horizontal plane and also dips successively downwards following the rotating movement of the drive body.

FIELD OF THE INVENTION

The present invention generally relates to a marine propulsion system,generally referred to as a vessel or boat drive, for use in watervehicles having an inboard engine and of the type in which the drivesystem with the propeller shaft extends through the stern of the boat,substantially straight out therefrom and is enclosed in a drive body,and in which the propeller shaft has, at the outer end thereof, apropeller, preferably of the surface drive type, and in which thesteering of the boat is done by operating the drive body itselt. Theinvention is more particularly concerned with a new type of steeringmechanism for such a marine drive system.

BACKGROUND OF THE INVENTION

A boat drive of this type is known from U.S. Pat. No. 4,645,463 (H MArneson) which patent discloses a structure in which the drive body isformed with a ball over which the drive is connected to the drive enginewhich is mounted inside the boat, and in which said ball is journalledin a ball carrier which is mounted at the stern of the boat, and inwhich the apparatus comprises two external hydraulic cylindersinterconnecting the stern of the boat and a part of the drive forrotating the drive in the horizontal plane for the purpose of turningthe boat, and in which there is an additional hydraulic cylinder formaking it possible to trim (tilt) the drive by rotating the drive up ordown in the vertical direction about the point of rotation of the saidball.

A boat drive of this type having a water surface driving propeller ishighly advantageous as compared with the so called Z-drive types, andabove all the drive causes less flow losses and less power lossesdepending on existing angle gear drives and transmission gear sets.Depending on the simple structure of the drive it is also cheaper tomanufacture, more effective and apt to less wear and has less sources oferror than many other types of boat propulsion drives.

The apparatus known from U.S. Pat. No. 4,645,463 indeed includes theadvantages of a drive being a straight, surface water driving propulsiondrive, but it is disadvantageous in that the ball and the ball carrierare subjected to strong stresses; in that certain plays may appear inthe steering means thereof and in that the hydraulic cylinders for thetrimming (tilting) and for the steering operations need to be servicedand maintained, are subjected to wear and are sensitive to ruptures andleakage in the hydraulic conduits, in particular since said parts arelocated on the exterior side of the boat, behind the stern of the boat.Normally there is also a need for long conduits and/or hoses from thepropulsion drive at the outside of the boat to the maneuvre place insidethe vessel or boat.

SUMMARY OF THE INVENTION

Therefore, the object of the present invention is to suggest apropulsion drive for an inboard-outboard motor of the type in which thedrive has a surface driving propeller which extends through the stern ofthe boat and substantially straight back therefrom, and in which thepropulsion drive is formed

- so that the boat can be steered without the assistance of hydrauliccylinders or equivalent axial power motors placed on the exterior sideof the boat,

- in which the propulsion drive has no actuation means at all providedon the exterior side of the boat whether for trimming the drive or forsteering the boat,

- in which both the trimming and the steering of the drive is made bymeans of actuation means placed inside the complete drive structure andat the interior side of the boat or vessel hull,

- and which has an improved back driving capacity as compared withpreviously known systems of the same general type.

BRIEF DESCRIPTION OF THE DRAWINGS

Further characteristics and advantages of the invention will be evidentfrom the following detailed description in which reference will be madeto the accompanying drawings.

In the drawings FIG. 1 is a side view in a vertical cross section of anembodiment of a propulsion drive according to the invention. FIGS. 2aand 2b are in combination an enlarged view of FIG. 1. FIG. 3 is afragmentary vertical cross section through a drive according to theinvention in its neutral trim position. FIG. 4 is view similar to thatof FIG. 3 showing the drive trimmed up a maximum angle and FIG. 5similarly shows the drive trimmed down a maximum angle. FIG. 6 is afragmentary perspective view of a part of the drive showing the trimmingmotor and the mounting of the steering cylinders. FIG. 7 is adiagrammatical rear view of the drive according to the invention showingthe movement of the propeller or propellers when turning the boat in onedirection or the other.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

For the sake of clarity the inboard boat engine has been omitted, but itshould be noted that the engine may be directly or indirectly connectedto the propulsion drive by any known means, and that drive couplingbetween the engine and the propulsion drive may be of any known type anddoes not influence the invention.

As conventional the propulsion drive according to the invention extendsthrough the stern 1 of a boat or a vessel and is mounted on said sternby means of a mounting ring 2. The drive generally comprises a mountingor bearing body 3 provided at the interior side of the boat hull, atrimming or tilting mechanism 4, a steering mechanism 5, a drive body 6and a propeller mechanism 7.

The drive is mounted close to the bottom 8 of the boat. The boat shouldbe of the fast running and preferably planing type. For obtaining thebest function of the invention the stern should be rather long, slopingrearwardly, for instance sloping at an angle of between 20° and 40°, orpreferably between 22° and 30°. In the case illustrated in the drawingsthe stern has a pitch angle of 25° to the horizontal plane. Because ofthe unusually long sloping stern there is obtained, when adjusting thepropellers for rearward driving, a forwardly directed flow of waterwhich smoothly follows the shape of the stern rather than being thrownagainst the stern, which would in turn reduce the back driving capacity,such as is usual for boats having a more steep to vertical extendingstern. Therefore the apparatus of the invention has an improved backdriving capacity.

The mounting ring 2 is formed with a radially outwardly extending outerflange 9 and a radially inwardly extending inner flange 10 and with asleeve portion 11 between said flanges 9 and 10. The outer flange 9 isarranged to be mounted on the exterior side of the stern 1, and theinner flange 10 with the sleeve portion 11 is adapted to carry theentire drive body 6.

For the purpose of mounting the drive on the stern a bore, preferably acircular bore 12, is cut out of the stern 1, and into said bore themounting ring 2 is introduced with the flange 9 thereof in contact withthe outer surface of the stern around said bore 12. On the inner side ofthe stern there are several screw-nut connection means, and an allaround extending flange 13 of the bearing body 3 is connected to themounting ring 2 over a connection ring 14, and the entire structure isscrewed to the stern under water sealed conditions by means of bolts 15.

The bearing body 3 is formed as a closed, water sealed casing which,over a double ball bearing 16 and an intermediate slide box 17 for theinput drive shaft 18, is connected to an inboard engine (notillustrated). The end of the input drive shaft 18 is formed with anintermediate drive shaft comprising two spaced universal joints 19a and19b and an intermediate sleeve 19c, which intermediate drive shaft 19a-cgives a constant angle speed and eliminates un-even torque and thrust inthe transmission joints. The ball bearing/slide box 16-17 which is ofknown type, allows an axial movement of the combined drive coupling.

As best seen from FIG. 2b a propeller shaft 20 is connected to theoutput end of the rear universal joint 19b by a flange 21 thereof. Thepropeller shaft 20 is journalled in the drive body 6 over two spacedroller bearings 22 and 23, which roller bearings 22 and 23 are mountedin a bearing sleeve 24 which in turn is fixedly mounted at the end ofthe drive body housing 25 via a screw connected locking ring 26, suchthat the propeller shaft 20 can take pressure forces, both in theforward and rearward directions thereof. A seal 27 at the end of thepropeller shaft 20 prevents water from entering the drive body 6.

The propeller mechanism 7 is of known type and is therefore notdescribed in detail. The propeller or the propellers preferably areformed with propeller blades 28 of variable pitch type and which can beadjusted to various angles so that said propeller blades, by beingangle-adjusted, can be set into forward or rearward propulsion or anidle drive positions. The adjustment of the propeller blades is made bymeans hydraulic pressure fluid entering the propeller shaft 20 andpassageways (not illustrated) in the propeller shaft through one or morehydraulic valves 29. The set position of the propeller blades istransferred to the maneuvre place by means of an indicator 30.

The trim mechanism 4 and the steering mechanism 5 are formed as anintegral unit which is connected between the mounting body 3 and thedrive body 6. The trim mechanism is screw connected to the mounting ring2 by means of the connection ring 14.

Referring in particular to FIG. 2a the trim mechanism 4 generallycomprises two co-operating adjustment rings, referred to below as thefirst or inner adjustment ring 31 and the second or outer adjustmentring 32. The surfaces 33 of said rings 31, 32 facing each other areinclined. In the illustrated case the two adjustment rings 31 and 32have an indentation angle of about 10°, whereby the drive body 6 can betilted or trimmed 10° up, see FIG. 4, or 10° down, see FIG. 5, from aneutral position, FIG. 3, but it is obvious that the conicity may bevaried with respect to the desired capability of "trimming" the drive upand down, resp. The two rings 31 and 32 are rotatable in relation toeach other and in relation both to the mounting ring 2 and to the drivebody 6. The adjustment rings 31 and 32 are mounted so that, in theneutral positions of the rings, the thinnest and the thickest ringportions, resp. are in contact with each other. The inner ring 31 isformed with a radially outwardly extending collar 34 by means of whichit is rotatably clamped between the connection ring 14 and a collarsurface 35 at the inner flange 10 of the mounting ring 2, and for thepurpose the connection ring 14 is screw connected at 36 to the mountingring 2. At the top of the second ring 32 an inner rack ring 37 is screwconnected at 38 and the second ring 32 with the rack ring 37 isrotatably clamped to the first or inner ring 31 by means of a lockingring 39 which is screw connected to said inner ring 31. A guide ring 40is rotatably mounted in a recess at the bottom surface of the secondring 32 and said guide ring is screw connected to the end surface orguide surface 41 of the drive body 6. The guide ring 40 with the drivebody 6 is rotatably clamped to the second ring 32 by means of a lockingring 42 which is screw connected to the second ring 32.

Thus the inner ring 31 is rotatable in relation to the mounting ring 2,to the connection ring 14 and to the second ring 32; and the second ring32 with the rack ring 37 is rotatable in relation to the first ring 31;and the drive body 6 with the guide ring 40 is rotatable in relation tothe outer or second ring 32.

The trimming of the drive body up or down is made by rotating the twoadjustment rings 31 and 32 in opposite directions from a neutral trimposition. See FIGS. 3-5. To this end the apparatus is formed with ahydraulic motor 43 which is supplied with pressure fluid over conduits44 and 45 and is drained by a third conduit 46. The hydraulic motor iscombined with a gear box 47 having a first and a second gear 48 and 49.The hydraulic motor 43 with the gear box 47 is mounted in a recess 50 inthe first ring 31 for rotation in common with said first ring 31. Themotor 43 is maintained at a fixed radius by a rotation rod 51 which ismounted at the top of the housing 52 of the mounting body 3concentrically with the rings 1 and 32.

The connection ring 14 is formed with an inner, ring-formed rack 53,which rack is thereby stationarily mounted in relation to the mountingbody 3. The gear 48 of the hydraulic motor 43 is cooperates with thestationary inner ring rack 53, and by actuating the hydraulic motor 43and thereby rotating the gear 48 the motor with the gear box 47 rotatesin one direction or the other on the stationary inner rack 53. Therebyalso the first or inner ring 31 is rotated together with the motor 43.The gear 49 of the hydraulic motor 43 cooperates with the inner gear 37of the second ring 32 and it is arranged to rotate the second ring 32 ina direction which is opposite to the movement of the first ring 31 andat a speed which is the same as the speed of the first ring 31. Thismeans that the gear 49 rotates at twice the speed of the gear 48.

By actuating the hydraulic motor 43 the gear 48 engaging the stationaryrack ring 53 causes the motor 43 to rotate on said rack ring 53, andthereby the first or inner ring 31, on which the motor 43 is mounted, isalso rotated in one direction or the other in relation to the mountingbody 3, and concurrently therewith the gear 49 rotates the second ring32 in the opposite direction and with twice the gear speed, wherebydifferent adjustment ring combinations are obtained. FIG. 3 shows theapparatus in a neutral position, whereby the motor 43 is located at thetop end of the mounting body 3 and the thickest and thinnest portions ofthe rings 31 and 32, resp. contact each other. By rotating the motor 43with the second ring 32 in one direction (counter clockwise as seen frominside the boat) as illustrated in FIG. 4 of the drawings the thickestportions of the two rings 31 and 32 contact each other at the bottomportion of the mounting body 3 and the thinnest portions of the tworings 31 and 32 contact each other at the top end of the mounting body3, and in this case the drive body is trimmed maximum upwards, in theillustrated case at an angle of 10° from the neutral position. FIG. 5illustrates the apparatus after the hydraulic motor 43 is operated inthe opposite direction (the clockwise direction as seen from inside theboat) whereby the drive body is trimmed maximum downwards, in theillustrated case 10° downwards.

The end face or guide end 41 of the drive body 6 is circular and saidend of the drive body is rotatably mounted in a groove of the secondring 32 of the trim mechanism 4. For rotating the drive body 6 inrelation to the mounting body 3, thereby turning the boat in thestarboard or port direction, there is a hydraulic cylinder 54 mountedinside the drive body 6 on each side of the sleeve 19c and the propellershaft 20. Each hydraulic cylinder 54 is mounted with the cylinder partthereof in an ear 55 which is fixedly connected to the bearing sleeve24; and with the piston rod part thereof in an ear 56 which is fixedlymounted in the housing 52 of the mounting body 3.

Since the hydraulic cylinders 54 extend at a specific angle to the slidesurface at the drive body guide end 41 and the second ring 32 anactuation of the hydraulic cylinders introduces a rotary force betweenthe drive body 6 and the mounting body 3 which force causes the drivebody to rotate with the end 41 thereof in the slide groove of the secondring 32, and thereby in relation to the mounting body 3.

Since further the connection surface of the mounting body 3 at the stern1 of the boat is designed so as to form a certain angle to the verticalplane, the propeller or propellers at the outer end of the drive body 6is/are caused to make a double movement upon a steering function, namelyboth a rotating movement in the horizontal plane, causing the boat toturn, and also a dipping of the propeller(s) in the vertical direction,said double movement resulting in a tendency of the boat to turnvertically inwardly to the turning centre, just as happens upon turningwith a bicycle. Said turn-over movement inwardly to the turning centeris a valuable function which both contributes to a stabilizing of theboat and also eliminates the feeling of discomfort which will otherwiseappear, something that is especially noted in catamarans, hydrofoilboats, boats having a high center of gravity, etc.

Normally the propulsion drive takes a predetermined horizontal drivingposition which is, in the illustrated case, at an angle to thehorizontal plane of for instance four degrees, at which position thereis a fully laminar flow of water from the bottom 8 of the boat and pastthe bottom side 57 of the drive body 6 and also the other parts of thedrive is fully laminar. Therefore there are practically no flow losses,not even at high speeds. Considering the load and speed etc. of theboat, or by driving the boat in shallow water it may be desired to trimthe drive up (or down) and this is done by rotating the trim drive motor43, whereby the racks 53 and 37 cause a rotation of the inner and outerrings 31 and 32 in opposite directions so that the inclined surfaces 33of said rings take a changed mutual position, whereby the drive issuccessively tilted up or down (compare FIGS. 3-5) depending on in whatdirection the motor 43 is rotated. This change of trim position can verywell be made while running the boat and it is made without any influenceat all on the steering function.

The steering is made solely by rotating the drive end or guide head 41by actuating the steering cylinders 54, whereby the drive body 6 is bothrotated in the horizontal direction and is dipped successively downwardsin the vertical direction in relation to the mounting body and the sternof the boat, and whereby the boat is also successively turned verticallyin the direction towards the turning center of the boat.

    ______________________________________                                        Reference numerals                                                            ______________________________________                                         1 stern          31 inner adjustment ring                                     2 mounting ring  32 outer adjustment ring                                     3 mounting body  33 cone surface                                              4 trimming mechanism                                                                           34 collar (of 31)                                            5 steering mechanism                                                                           35 collar surface                                            6 drive body     36 screw                                                     7 propeller mechanism                                                                          37 inner rack ring (of 32)                                   8 bottom (of boat)                                                                             38 screw                                                     9 outer flange (of 2)                                                                          39 locking ring                                             10 inner flange (of 2)                                                                          40 guide ring                                               11 sleeve portion (of 2)                                                                        41 end surface, guide ring                                  12 bore (of 1)    42 locking ring                                             13 flange (of 3)  43 hydraulic motor                                          14 connection ring                                                                              44 conduit                                                  15 bolt           45 conduit                                                  16 ball bearing   46 drain conduit                                            17 slide box      47 gear box                                                 18 input shaft    48 gear                                                     19a universal joint                                                                             49 gear                                                     19b universal joint                                                                             50 recess                                                   19c sleeve        51 rotation rod                                             20 propeller shaft                                                                              52 housing (3)                                              21 flange         53 inner rack ring                                          22 roller bearing 54 hydraulic cylinder                                       23 roller bearing 55 ear (at 24)                                              24 bearing sleeve 56 ear (at 3)                                               25 drive body housing                                                                           57 bottom (of 6)                                            26 locking ring                                                               27 seal                                                                       28 propeller blade                                                            29 hydraulic valve                                                            30 indicator                                                                  ______________________________________                                    

I claim:
 1. A marine propulsion drive apparatus for an inboard engine inwhich the input drive shaft with its propeller shaft extends generallyhorizontally through the stern of a boat, comprising:a drive bodyextending generally horizontally substantially straight out from thestern of the boat and having a propeller attached to the drive body andextending generally axially and horizontally at the outer end thereof,said propeller arranged and designed to operate at the water surface,and wherein steering of the boat is accomplished by operating the drivebody itself, a common connection surface of the drive body and the sternof the boat having an obliquely upwards-rearwards slope from the bottomof the boat, the connection surface of the drive body at the stern ofthe boat being rotatably mounted about an axis which is perpendicular tosaid connection surface, whereby the boat is turned by rotating theentire drive body in one direction or the other about said connectionsurface.
 2. An apparatus according to claim 1, wherein said contactsurface of the drive body is circular.
 3. An apparatus according toclaim 1, wherein the rotatable connection surface of the drive body ismounted such that the propeller at the outer end thereof, upon rotationof the drive body about said axis and turning of the boat, both rotatesin a horizontal plane and moves vertically downwardly by an amount whichis related to the extent of the horizontal rotating movement.
 4. Anapparatus according to claim 1, wherein the connection surface lies atan angle of 20° to 40° relative to a horizontal plane.
 5. An apparatusaccording to claim 4, wherein the angle of the connection surfacerelative to a horizontal plane is between 22° and 30°.
 6. An apparatusaccording to claim 1, wherein the drive body is mounted such that thepropeller shaft, during running of the boat, normally forms an angle ofbetween 3° to 6° relative to a horizontal plane, and wherein said anglecan be trimmed successively upwardly and downwardly from said normalangle a maximum of approximately 10°.
 7. An apparatus according to claim1, including a steering mechanism which is operationally connected to atrimming mechanism, which trimming mechanism comprises two cooperatingadjustment rings having surfaces which are inclined relative to theirrespective bases, which bases are parallel to each other, the inclinedsurfaces being in direct contact with each other, an outer one of saidadjustment rings carrying the drive body, the two adjustment rings beingrotatable relative to each other to allow different adjustment ringcombinations for trimming the drive body upwardly or downwardly,respectively.
 8. An apparatus according to claim 7, wherein the steeringmechanism and the trimming mechanism are actuable independently of eachother.
 9. An apparatus according to claim 1, wherein the steeringmechanism comprises two hydraulic cylinders which are mounted inside ofthe drive body on each side of a drive shaft, said hydraulic cylindersbeing connected at one end to the drive body and at their other ends toa stationary housing of the apparatus.